Liquid pressure accumulator systems

ABSTRACT

A liquid pressure tank is provided for storing liquid under pressure for use in domestic or commercial reticulated supply of the type having an impervious diaphragm dividing the tank into an air chamber and a liquid chamber, a constant amount of air being maintained in the chamber under pressure. A liquid pump and pressure switch system is provided for maintaining liquid in the chamber between preset pressure limits, the diaphragm being so configured and secured to form a pistonlike portion within the tank which reciprocates under variation of liquid pressure to minimize wrinkling or stretching of the diaphragm. Also a fixed plate can be arranged over the liquid outlet as protection from rupturing of the diaphragm at low liquid levels.

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liquid under pressure for use in domestic or commercial reticulatedsupply of the type having an impervious diaphragm her and a liquidchamber, a constant amount of air being maintained in the chamber underpressure. A liquid pump and pressure switch system is provided formaintaining liquid in the chamber b [54] LIQUID PRESSURE ACCUMULATORSYSTEMS dividing the tank into an air cham plate protection from rups.

etween preset pressure limits, the diaphragm being so configured andsecured to form a pistonlike portion within the tank which reciprocatesunder variation of liquid pressure to minimize wrinkling or stretchingof the diaphragm. Also a fixed can be arranged over the liquid outlet asturing of the diaphragm at low liquid level 11B, 1 M FUZ m mum a mwm mmum W n m mm 0 0 mm mm M min A l "f l 1 10 1 h w d C SLHM 3 .H W M 3LIQUID PRESSURE ACCUMULATOR SYSTEMS This invention relates to liquidpressure tanks in which a liquid such as water is stored under pressurefor use in domestic or commercial supplies. Thus one importantapplication of pressure tanks is in rural districts where a pressurizedwater supply is not generally available and where it is necessaryparticularly for cleaning purposes or the like on primary or industrialpremises. Pressure tanks for domestic home use also have appeal whereonly a low-pressure water supply is available.

The present invention will refer specifically to the supply of water,however it will be understood that the tank can be arranged to supplymost fluids in a pressurized form.

The pressure tank is of the type in which a reserve supply of water isheld under pressure. The tank is divided into two areas by a flexiblediaphragm; one area containing water and the other compressed air. Wateris arranged to be pumped into the tank against the pressure of airexerted on the diaphragm so that the column of air is displaced orcompressed. Once a predetermined pressure has been reached the pump isautomatically stopped.

In a practical installation the tank is connected to a home water supplyso that upon opening of a tap in the home pressurized water is drawn offfrom the tank, when the pressure falls to a predetermined minimum thepump is restarted and the tank is replenished until maximum pressure isagain reached.

The major problems associated with this apparatus lie in attainingtrouble-free operation of the diaphragm which must be substantiallyair-impervious and have good resiliency. Furthermore undue crumpling orstretching of the diaphragm should be avoided in normal operation inorder that its life expectancy can be increased considerably. Furtherproblems are associated with the construction of the water outlet of thetank whereby the diaphragm will not be ruptured by pressure of airimpinging thereon when the water tank is empty. Various constructions ofoutlet valves have been proposed in the prior art for the purpose ofretaining some residual water in the tank to prevent such rupture,however these valves have not proved completely satisfactory in practicein that, due to their inherent construction, full flow of pressureliquid from the tank at times of maximum demand is reduced and also suchvalves tend to close prematurely before the complete storage of waterhas been used.

lt is a principal object of this invention to provide a fluid pressureaccumulator tank of the type having a diaphragm and in which thediaphragm is of improved construction.

It is a further objective of the invention to provide improved fluidoutlet means for the fluid storage in which the abovementioneddisadvantages are effectively countered.

According to the present invention there is provided a pressure liquidaccumulator tank including a hollow housing, a diaphragm secured withinand dividing said housing into an air chamber and a liquid chamber, twoports in said housing one of each communicating with each chamber foradmission of air under pressure to said air chamber and liquid underpressure to said liquid chamber respectively, the amount of airmaintained in said air chamber being substantially constant when in use,the arrangement being such that as the quantity of liquid in said liquidchamber varies said diaphragm will move between two positions withinsaid housing representing minimum liquid pressure and maximum liquidpressure, the position of securement and the configuration of thediagram being such that a pistonlike membrane portion is formed forreciprocatory movement along the length of said housing to preventexcessive wrinkling or stretching of said diaphragm during saidmovement.

Conveniently the liquid chamber is bounded solely by said diaphragm anda keeper plate securely sealing said diaphragm to said housing. Thekeeper plate includes the liquid port. ln one arrangement the liquidport is covered by a plate extending substantially parallel to andspaced from said keeper plate, said plate being adapted to receive inabutting relation portion of said diaphragm, said keeper plate includingan annular shoulder of larger diameter than said plate, the spacebetween said shoulder and said plate defining said liquid port, saidshoulder having an inclined face adjacent said plate against which aportion of the diaphragm also abuts to effectively seal said liquid portwhen liquid pressure falls to a minimum. ln an alternative form theoutlet liquid port may be provided by a simple multiported plastic orlike outlet piece snapped into an aperture in the keeper plate andagainst which the diaphragm abuts. The ports are of such diameter as toprevent rupturing of the diaphragm.

In one form said diaphragm in integral form includes two substantiallyconcentric portions extending substantially parallel to the sidewalls ofsaid housing one end of the outer concentric portion being free andadapted to be secured to said housing by the end keeper plate which isarranged to seal said housing, one end of the inner concentric portionbeing connected to the other end of said outer concentric portion, thediaphragm further including a membrane portion which extendssubstantially across said housing to join the other end of said innerconcentric portion. The material of said diaphragm is of flexible, andsubstantially air-impervious, butyl rubber material.

The invention will now be described in further detail having referenceto a practical arrangement which will be described with reference to theaccompanying drawings in which:

F l0. 1 is a sectional view of a tank assembly in one arrangement of theinvention.

FIG. 2 is a sectional view of a general assembly of a furtherarrangement in accordance with the present invention.

F l6. 3 is a partial sectional view of a modified outlet port.

The pressure tank 1 of one arrangement as shown in F IG. 1 is ofcylindrical form having curved ends 1a, lb, one end laforming part ofthe air chamber 2 and having a one-way valve 3 therein for charging thischamber with compressed air.

The other end of the tank housing is closed with a discal keeper plate 4which includes an outlet duct 5. A diaphragm 6 manufactured inaccordance with the invention is arranged to be secured within thehousing by said keeper plate 4. In large high-pressure tanks thediameter of said keeper plate 4 is preferably maintained relativelysmall and is arranged to interconnect with a ring 7 about the open endof the housing proper. The ring 7 has studs (not shown) therein forsecurement of said plate and a free end 6 10f said diaphragm 6 isarranged to be wrapped partially around said ring 7 prior to fitting andsecurement of said keeper plate 4.

In an alternative form as shown in FIG. 2 suitable for smalllower-pressure tanks the keeper plate 14 is of similar diameter to thatof the housing 10 and secures to a studded ring flange 17 extendingaround the housing circumference. The edge portion 16aof the diaphragm16 is conveniently beaded to ensure a good seal when compressed betweensaid keeper plate 14 and said flange 17. In this figure a schematicarrangement of the motor 20, pump impeller 21 and pressure switch 22 isshown in assembly. The pump is of a centrifugal jet, easypriming type.The pressure switch 22 is preferably adjustable and controls operationof the motor within preset liquid pressure limits.

ln this arrangement liquid at low pressure is drawn in through port 24and pumped under high pressure into chamber 26 for supply either tooutlet port 25 or through hose 23 to the pressure vessel. The pressureswitch 22 is arranged to disconnect the motor 20 upon the pressure underthe diaphragm l6 reaching a preset maximum. Further supply of liquid isprovided from the tank until the pressure falls to a preset minimumwhereupon the switch 22 connects said motor 20 and pumping recommencesto provide further pressurized supply of liquid.

in high-pressure tanks such as that depicted in FIG. 1 the outlet port 5in the keeper plate 4 is covered by a circular plate 8 spaced from theport 5. Furthermore the port 5 is surrounded by a chamfered shoulder 9.The shoulder 9 and the edge of the circular plate 8 presents a seatingsurface which is arranged to be contacted and sealed by said diaphragm 6during periods of minimum pressure in the tank. Sealing is arranged totake place only when a residual amount of water is left in the tank. Analternative form of outlet port is depicted in FIG. 3 comprising amultiported disc 9a of plastic or like material which presses orsnap-fits into the apertured keeper plate 4a, the disc ports being of asize to support the material of the diaphragm without rupturing thereof.

Thus it will be understood that with the combination of suitable butylrubber materials in the diaphragm and the construction of the outletport in the keeper plate, the possibility of damage to the diaphragm isminimized while full perfonnance in flow rates can be obtained from thepressure tank.

in a low-pressure tank as shown in FIG. 2 protection of the strong butylrubber diaphragm is not necessary. The diameter of the outlet andpressure of liquid being such that no rupturing is likely to occur.

An important feature of this invention is the construction andconfiguration of the diaphragm 6 and 16 referring to FIGS. 1 and 2respectively in the drawings. The free end 60 and 16a of the diaphragmin each instance is arranged to be secured within the housing adjacentthe liquid outlet end, and in these arrangements is in substantially thesame plane as the outlet. The diaphragm is formed with an upstandingouter portion 6b, 16b which extends from the free end substantiallyparallel to the walls of the housing 1 to 10 and then is turned througha U to extend back inside itself for a substantial distance to form aninner concentric portion 66, 16c whence a membrane portion 6d, 16d isformed to complete the diaphragm shape. The membrane portion 6d, 16d isadapted to move in pistonlike fashion from the liquid outlet end whereit is positioned at low pressures towards the other end, therebydisplacing and increasing the pressure of air in the air chamber as theliquid pump operates to increase the liquid pressure in the tank.

It has been found that the above described construction of the diaphragmtogether with its attachment at or near one end of the housing providesfor a rolling or peeling action as the membrane portion 6d, 16dreciprocates along the length of the housing according to variations inliquid pressure. Thus at maximum pressure the wall portions 6b, 6c and16b, 16c of the diaphragms extend along substantially parallel to thewall of the housing as shown by the dotted lines depicting the expandedposition of the diaphragms 6 and 16 in each figure but at low pressuresthe inside concentric wall portion 60, 16c of each diaphragm is housedwithin the outside concentric wall portion 6b, 16b. Thus, the outerconcentric wall remains substantially stationary while the inside wallpeels off or rolls on relative to this outer wall portion. in this way aminimum of crumpling or stretching is incurred by the diaphragm materialthus allowing for heavy-duty, air-impervious and flexible materials tobe used. Butyl rubber has been found to have excellent characteristicsin carrying this invention into effect. The use of pure butyl rubber inthe manufacture of the diaphragm is preferred, however it has been foundthat a mixture of at least 25 percent (chlorinated) butyl rubber withthe balance essentially natural rubber also has proved satisfactory.

It has been found that at relatively low pressures this material willnot rupture and accordingly protection from rupturing at the liquidoutlet is only necessary in the practical arrangement when relativelyhigh liquid pressures and flow rates applicable in larger systems areused.

lclaim: l. A pressure liquid accumulator tank comprising a hollowcylindrical housing, a generally cylindrically shaped diaphragmextending the length of said housing secured within a dividing saidhousing into an air chamber and a liquid chamber, the liquid chamberbeing interior of said diaphragm, two ports in said housing onecommunicating with each chamber for admission of air under pressure tosaid air chamber and liquid under pressure to said liquid chamber resectively, a keeper plate securing said diaphragm to one en of saihousing and includes the liquid port, said liquid chamber being boundedsolely by said diaphragm and said keeper plate, means for maintainingthe amount of air in said air chamber substantially constant when inuse, said means comprising an arrangement whereby as the quantity ofliquid in said liquid chamber varies said diaphragm will move betweentwo positions within said housing representing a minimum liquid pressureand a maximum liquid pressure, said diaphragm being integrally formedsolely of flexible rubber material and having two substantiallyconcentric portions extending substantially parallel to the sidewalls ofsaid housing, one end of the outer concentric portion being secured tothe housing by said keeper plate in sealing relation, one end of theinner concentric portion being connected to the other end of said outerconcentric portion, the inner concentric portion being joined to amembrane portion which extends substantially across the housing to closethe other end of said inner concentric portion, said keeper plate alsoincluding an annular shoulder and a rigid circular immovable plateextending parallel to and spaced from the surface of said annularshoulder and keeper plate thereby defining said liquid port, saidannular shoulder having a diameter larger than that of said circularplate, said fixed plate receiving in abutting relation a portion of saiddiaphragm membrane portion, said shoulder having an inclined factadjacent said circular plate, said shoulder and the edge of saidcircular plate forming a seating surface against which a portion of thediaphragm membrane portion also abuts to effectively seal said liquidport when liquid pressure falls to a minimum.

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1. A pressure liquid accumulator tank comprising a hollow cylindricalhousing, a generally cylindrically shaped diaphragm extending the lengthof said housing secured within and dividing said housing into an airchamber and a liquid chamber, the liquid chamber being interior of saiddiaphragm, two ports in said housing one communicating with each chamberfor admission of air under pressure to said air chamber and liquid underpressure to said liquid chamber respectively, a keeper plate securingsaid diaphragm to one end of said housing and includes the liquid port,said liquid chamber being bounded solely by said diaphragm and saidkeeper plate, means for maintaining the amount of air in said airchamber substantially constant when in use, said means comprising anarrangement whereby as the quantity of liquid in said liquid chambervaries said diaphragm will move between two positions within saidhousing representing a minimum liquid pressure and a maximum liquidpressure, said diaphragm being integrally formed solely of flexiblerubber material and having two substantially concentric portionsextending substantially parallel to the sidewalls of said housing, oneend of the outer concentric portion being secured to the housing by saidkeeper plate in sealing relation, one end of the inner concentricportion being connected to the other end of said outer concentricportion, the inner concentric portion being joined to a membrane portionwhich extends substantially across the housing to close the other end ofsaid inner concentric portion, said keeper plate also including anannular shoulder and a rigid circular immovable plate extending parallelto and spaced from the surface of said annular shoulder and keeper platethereby defining said liquid port, said annular shoulder having adiameter larger than that of said circular plate, said fixed platereceiving in abutting relation a portion of said diaphragm membraneportion, said shoulder having an inclined face adjacent said circularplate, said shoulder and the edge of said circular plate forming aseating surface against which a portion of the diaphragm membraneportion also abuts to effectively seal said liquid port when liquidpressure falls to a minimum.